Wallet: earn → milestone → redeem

A collection game credits a wallet currency on every play; once the balance reaches a milestone threshold, the player redeems it for a real prize.

Earning (inside Play)

Redeeming (manual claim or spend-exchange)

Reading the wallet

Proven by make e2e-wallet: two plays accrue 2 lucky_star, the milestone shows unlocked, redeem grants the prize, and a second redeem returns ALREADY_EXISTS.